Chemical Engineering Seminars - Controlling and probing weak colloidal interactions from the nano to the micro scale
Event details
| Date | 26.02.2016 |
| Hour | 16:15 › 17:15 |
| Speaker |
Prof. Frank Scheffold Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland |
| Location | |
| Category | Conferences - Seminars |
I will discuss a few examples how we can manipulate and probe soft interactions between small colloidal spheres ranging from 200nm to several microns. The control and understanding of these interactions is of fundamental interest in condensed matter physics but also of great importance for the design of new materials. I will mainly focus on three types of colloids – charge stabilized polymer beads, emulsion droplets and microgels. These three popular model systems are rather well defined and the properties can be analyzed and tuned by different means. I will first speak about strongly screened charge stabilized polymer beads with a solid polymer core. These systems essentially behave as hard spheres. I will present an experiment on a pair of particles where we demonstrate that the interaction potential can be tuned externally by inducing ‘artifical van-der Waals’ attractive forces by embedding the particles in a very intense diffuse light cloud. I will then proceed to discuss two colloidal systems where the particles are deformable. First I will discuss the popular microgel particles where the swelling can be tuned by changing the solvent properties. These ‘smart colloids’ with tunable size and elasticity have attracted much attention because of their potential use as drug delivery agent or for tuning the flow properties of complex fluids. Here I will present a novel experiment where we have used STORM superresolution microscopy (nanoscopy) to study the swelling of individual microgel particles on the nanoscale. Finally I will conclude by presenting recent results on dense suspensions of nano- and micron sized emulsion droplets where we study the glass and the jamming transition from the fluid to the highly compressed regime using a combination of confocal microscopy, low-coherence light scattering and diffusing wave spectroscopy.
Practical information
- General public
- Free